6-months-old female Chihuaha, with suspicion of portosystemic shunt. An abdominal CT scan was performed.
Description
The hepatic parenchyma is reduced in size, preserving smooth and sharp margins, with homogeneous attenuation on the pre- and post-contrast series (blue arrows).
The portal vein progressively increases in diameter in its extrahepatic portion as it receives the different tributaries. At intrahepatic level, there is an aberrant large vessel (red arrows), which originates from the portal vein (PV) and extends along the left side of the liver inserting into the caudal vena cava (CVC) at the level of the hepatic ampulla (via the left phrenic vein). The insertion point of the shunt in the hepatic ampulla is close to the insertion of the central hepatic and left hepatic veins, which have a normal morphology with no signs of distension (blue and green arrows respectively). Cranial of the origin of the shunt, no intrahepatic portal vessels are clearly visible.
Both kidneys are prominent (blue arrows), while preserving a normal shape. Right kidney shows a small mineral foci located in the pelvis (pink arrows).
Diagnosis
- Aberrant vessel consistent with congenital left divisional intrahepatic portosystemic shunt (inserting into the CVC via the left phrenic vein).
- Intrahepatic portal branches not visible in the study, which may indicate that they are very small or absent.
- Microhepatia and mild bilateral renomegaly, secondary to the shunt.
- Small mineralization/nephrolith in right kidney.
Comments
The findings are consistent with an intrahepatic left divisional portosystemic shunt of congenital origin. Based on its morphology, the shunt inserts into the intrahepatic caudal vena cava via the left phrenic vein, and does not appear to involve the rest of the hepatic veins (ref. 1). According to the most recent literature and based on its morphology the type of shunt would be an “interlobar intrahepatic portosystemic shunt” (patent ductus venosus) (ref. 2).
The following articles might be of interest:
- Plested M.J. et al. Canine intrahepatic portosystemic shunt insertion into the systemic circulation is commonly through primary hepatic veins as assessed with CT angiography. Vet Radiol Ultrasound. 2020 Sep;61(5):519-530. doi: 10.1111/vru.12892.
- Walsh N.D. et al. Canine intrahepatic portosystemic shunts: Interlobar and intralobar classifications. Vet Radiol Ultrasound. 2023;64:646–660. Doi: 10.1111/vru.13252.
